The 3-digit factors of 1000 are 100, 125, 200, 250, 400, 500, 625.
All are multiples of 25. None are prime.
2
Anything three-digit would have to be a multiple, like 280.
No factor of 9 has three digits. 450 is a three-digit multiple of 150 (and of 9) with a digit sum of 9.
The largest two-digit multiple of six is 96.
1000000
1000000
Divide the two-digit number by the one-digit number. If the remainder is zero then the 2-digit number is a multiple and if not, it is not.
1000000
Easier than what? The easiest way to produce a three-digit number that is a multiple of 3 (has 3 as a factor) is to make sure the digits total to a multiple of 3. 123, 555, 498 are all multiples of 3.
There is no such number. If a multiple of 4 is a factor of 30, then 4 must also be a factor of 30, but 4 is not a factor of 30 (the factors of 30 are: 1, 2, 3, 5, 6, 10, 15, 30), thus no such number exists.
100000
999999